XR-75/Staton NuVinci Build

Okay, This project isn't near finished yet but I have been taking pictures at just about every step of the way. Heres a list of features that are going to be included on this build:
-Mongoose XR-75 dual suspension MTB, aluminum frame, steel rear triangle.
-Staton NuVinci drive with Mitsubishi TLE43 engine, half-lever left hand throttle/killswitch , right side NVshifter. Torsion bars.
-center handlebar mounted digital speedo.
-left handle bar end nashbar convex mirror.
-New aluminum nashbar Jaws pedals.
-double thick and slimed Bell innertubes
-Bell kevlar lined 26x1.75 road tires (thin but should allow this thing to be pedaled if need be.)
-Bottle and cage for extra fuel
-Bell comfort Gel seat (black)
-Finished and painted Staton hardware (gloss black to match rear triangle of bike.)
-Emaxi break levers with internal switches for brake light activation.
-Full lighting to New Hampshire moped standards. Enclosed in a soft (hard lined) black/silver lunchbox to be mounted to the left hand side of the Staton rack opposite the engine.
--55w Halogen headlamp w/ small rectangular enclosure and mounting hardware wired through a very efficient 12v turn dial dimmer switch to adjust brightness.
--A 7 LED taillamp that doubles as a brake light when wired with the Emaxi levers.
--Electrical master on/off switch and 12v battery gauge.
--5ah SLA battery.
--Charger port.
--Possibly an on the move charging system as well as I have a 1200mAh 12v power rectifier that I may be able to hook into a dynamo or DC brushed motor.
-All wires/cables to the staton rack are going to be run down (and through) the center of the frame and will be wrapped in spiral casing and zip tied clean and secure.


I would have this beast finished but I'm still waiting for the weather to get nice (clear and over 50F) so I can prime and paint the staton rack to match the bike. I've already done a lot of grinding and rounding to make the staton kit not appear as chunky. I have to say though this thing is rock solid. I've already mocked everything up and it should all fit together nicely. So here are the pictures. I have tons more but I've had to do the steps all out of order as I got the chance to do them so it would be more confusing to you folks than its worth.

Pic1: The mongoose last summer after a muddy thrillride down a trail near my house.
Pic2: Mongoose with NuVinci installed and cables run, torsion straps are backwards (was just measuring at the time) and heavy duty pedal chain.
Pic3: NuVinci out of the box.
Pic4: Mocked up rack to make sure everything would fit and work well.
Pic5: Cooler electrical box. Front pocket (with penguin) has the dimmer, switch and battery gauge mounted into plastic underneath. Unfinished.

 

[duivendyk]

Sorry to have confused you, 4 stroke engines inherently have a fairly flat torque characteristic and generally have good low-end torque 2 strokes are usually peakier,the intake& exhaust can be "tuned" to maximise torque&power,usually to improve performance at higher rpm .The objective is to suck the old charge out of the cylinder quickly by creating a negative pressure at the exhaust port,when it opens.With proper tuning they can be capable of astonishing power,over 150 HP/liter,but the powerband is pretty narrow.The old Kawasaki 2 strokes I used to ride were notorious in this regard.With a gearing like the NV hub this peakiness does not matter all that much,just keep it in the revs,you won't be doing wheelies with your rig anyway!.As far as torque goes,engine size corresponds to increased torque, regardless of engine type,the rpm range is pretty similar 3000/8000 rpm,but it is quite possible for instance that the 35 cc Subaru engine outdoes the Mitsu 43cc at the low end.Torque characteristics are not easy to come by for these engines,www.robinamerica.com gives quite a lot of useful info on the small SubaruRobin engines,I have never come across similar info for the Mitsu.,JJ

 

[stiche]

Great Information

Thanks duivyndik and SirJakesus.
I like the design of the Robin, it has proper valves like a bigger engine does instead of reed valves, not that I think there's anything wrong with a 2 stroke. I would prefer a 4 stroke since they run cleaner and supply torque better at lower revs, which I didn't realize before now. I thought the Nuvinci hub would do the job and yall have confimed that, thanks bunches!

 

[SirJakesus]

To tell you the truth I originally wanted a 4-stroke to get that low engine tone and to fill up directly at gas stations but the Honda GXH50 just looked too darn bulky for my tastes. The only happy middle ground in size and HP output was the mitsu. I think if I were to make another one of these for my girlfriend or whatever I'd probably go with the robin. The Honda33 is a bit more compact but I've heard great reviews of the robin Subaru engines.
Either way, If you choose to go with this kit no matter what engine you pick you shouldn't be disappointed. The shifting takes a bit of getting used to and it's pricey but you can't expect to get anything this tough and versatile anywhere else. I trust this thing going on longer rides than I ever have with my HT engines, it's just that solid and well engineered.

Expect to do a lot more work to set it up than a HT build aswell. I had my HT MTB together in a day (with errors of course) but the staton NV took me weeks of toiling to get perfect.

 

[duivendyk]

The Robin is a attractive design,the pushrod OHV is preferable to a Honda OHC (no camshaft&drivebelt).You can find lots of info on their Robinamerica website.Valves need to be adjusted though!,once in a while,and changing oil is not all that easy either,I think you have to suck the old oil out.If a larger version had been available,I would have certainly gone for it.These tiny engines are pushed pretty hard, in use.Treat it kindly.Also pay attention to my posts about installing the NV hub,there are some gotches out there.Good luck,JJ

 

[sparky]

Two questions...

(1) The hub doesn't come with the second freewheel, does it? I assume you had to buy the freewheel separately (which one?) and attach it yourself, right?

(2) Most engines seem to spin CCW. For example, the EH035 is typically on the left side of the bike, isn't it? Doesn't NuVinci need to spin CW and be on the right side??

 

[SirJakesus]

Both sprockets are on the right side of the NV hub. The smaller one to the far right is a freewheel for your pedal chain. The larger one next to the hub seems to be around 36 tooth or so freewheels but will turn when you pedal only. Due to this fact the staton gearbox also has a freewheel on it. It's this freewheel that staton will ask you what size you want when you order. He strongly suggested the 22t freewheel which yields around 32mph top speed. When you're pedaling both pedal and motor chains are moving HOWEVER this doesn't seem to create any perceptible amount of drag. The bike isn't very hard to pedal especially with the aid of the hubs low range. Just feels like you're on a normal bike hauling groceries or camping gear.
The kit comes with absolutely everything you're going to need to motorize a bike. Just make sure you have some rack mounting holes over the rear dropouts on your bike. I had to drill them out a bit to get statons bolts to fit through but everything is connected so tightly it might as well be a part of the bike now.
If you don't have rack mounting holes on your frame check out the pictures on statons site, there are some people who made brackets to fit around the frame tubes in order to hook up the rack. You could probably order a couple 4-hole happytime tensioner brackets and just cut off the excess pieces you dont need.

The hardest part of this install is bending and positioning the torsion straps. Make sure you have a vise and propane torch available or preferably some real metalworking tools. It takes awhile to get it right, I even screwed up a strap at first but replaced it with some Lowes steel.

 

[duivendyk]

I concluded that trying to bend these straps was a lost cause,unless you take a course first in smithology.I elected to connect the strap to the torsion bar oriented at about 60 degree to the horizontal with twin 1/4" bolts,so that the assembly becomes a rigid unit, fashioned contoured aluminum connecting blocks to fit above&below the rearfork leg,I drilled a hole in each and two holes in the strap to bolt the whole shebang together,that makes a pretty solid assembly.
You have to bear in mind that by far the largest torque reaction is in the UPWARD !! direction.(See my NV posts).It sounds pretty complicated but it is doable and you can makes things fit as you go along.It helps to have a drillpress, some stock & metal working tools.Bending those 1/8 " straps ,if I tried it I would bend the thing in a U shape and fashion a contoured block to close the U from below & put a bolt through it all.Staton should make better hardware,what's really needed is an "L" shaped torsion bar running underneath the fork and a properly bent strap + hardware to fit the fork.Good luck,JJ

 

[sparky]

Both sprockets are on the right side of the NV hub. The smaller one to the far right is a freewheel for your pedal chain. The larger one next to the hub seems to be around 36 tooth or so freewheels but will turn when you pedal only. Due to this fact the staton gearbox also has a freewheel on it.

Hmm... that's why it didn't make sense to me -- the gearbox! I wasn't looking too hard at the kits before, but last night I noticed the gearbox in the pics. It was a bit confusing to me why you'd need a gearbox... but I'm now understanding this gearbox isn't for changing gear ratios, it's for changing the rotation of the driveshaft.

 

[duivendyk]

You need in the range of 25 to 40 overall reduction between the engine,18.75 is in the Staton gearbox,with a 18T output sprocket and the NV sprocket of 27 T ,you get a wheel speed of 213 rpm for an engine rpm of 6000, and with a. 26" wheel and 1.0 hub ratio, a road speed of 16mph a max.speed (1.87 hub ratio) of 30 mph and a min. of 8.5 mph.(0.53 hub ratio)The reduction is needed to match the engine to road speed and get enough drive force,which is proportional to the reduction ratio.Larger engines with more torque can use less reduction and get you to go faster,smaller ones need more.If hills are not a problem,lower ratios can be used,conversely if they are, a larger engine and/or a larger reduction is indicated,JJ

 

[SirJakesus]

Just an update and a few more pictures! The mitsu is breaking in nicely and has quite a bit of power now, enough to sling dirt and high tail over just about anything I'm capable of riding through. Shes a real mover and all the work was well worth it. Thanks for the comments and checking out my pics!

These are just a few more angles to give you fellas a better look at 'er.